The link shows government spending per student as a percentage of GDP per capita, rather than overall government spending per capita. This figure can get distorted when there are more students in the system for any reason (such as due to private investment).
> since those places tend to make it harder to go to college, since taxpayer pressure on cost reduces opportunity.
This does not follow. Rather, having more students decreases the per-student government expenditure figure, even as the burden on the taxpayer stays the same.
As a percentage of GDP, US government expenditure on tertiary education is roughly in the middle of what various countries in Europe spend.
https://www.statista.com/statistics/707557/higher-education-...